Rotary pump or compressor



R'. 1. CHAOKNELL.

' ROTARY PUMP 0R COMPRESSOR.

APPLlcATloN r'lLED MAY 1o. 1920.

- Patented Nov. 23, 1920.;

2 SHEETS-.SHEET 1.

R. 1. cRAcKNELL. ROTARY PUMP 0R COMPRESSOR.

1920. 2 sHEETs-sRsgT 2.

APPLICATION FILED MAY I0. 1920.

Patented Nov. 23

RICHARD'JOHN CBACKNELL, STREATHAM, ENGLAND.`

RQTARY PUMP on.' coMPREssoR.

. s. Specification of Letters Patent. Patented N0V 23, 1920.

Application filed May 10, 1920. Serial No. 38Q,273.

T o all whom t may concern Be it known that LRIcHAnn JOHN CRACK- NELL, a subject of the King of England, and residing at Streatham, Surrey, in England, have invented certain new and useful Improvements in Rotary Pumps or Compres` sors, of which the following is a specification.

This invention relates to rotary pumps or compressors of the type in which an inner rotary member is mounted eccentrically within an outer. rotary member and vboth members are adapted to rotate at the same angular velocity within a fixed outer casing. The bject of this invention is to simplify the construction of such apparatus, to provide a machine which is fluid tight while absorbing less power than those hitherto proposed, and to provide improved means for causing the simultaneous rotation of the two rotary members in the same. direction4 and at the same angular velocity.

According to this invention means are provided for maintaining a seal of liquid between relatively moving parts of the apparatus to lubricate all wearing parts and prevent leakage of compressed fluid past such relatively movingaparts. Further, this liquid may serve the additional purpose of carrying'away the heat of compression when the apparatus is used for compressing some fluid. The coupling mechanism connecting the tWo rotary members is mounted within the outer rotary member and is disposed in a chamber formed between one end of the latter and the adjacent end of the inner rotary member. The sealing and lubricating liquid circulates from the lower part of the xed outer casing through suitablev inlets communicating through conduits With the bearings of the rotary members, with the chamber containing the coupling mechanism, and with all portions of the rotating members Which-are in contact and between which relative movement occurs.

The inner rotary member carries one or more sliding vanes and a supply of lubricant is maintained over the inner end of the vanes which thus serves both to lubricate the vanes and to prevent leakage of the fluid to be compressed past any of their edges in the manner hereinafter described.

The invention is particularly applicable' stance` for refrigerating purposes and one f orm of apparatus embodying the invention .suitable for these purposes is illustrated by way of' exampxle in the accompanying drawings, in whic Figure l is a central longitudinal section.

Fig. 2 is a cross section of the rotary members on the line 2 2 of Fig. 1.

Figs. 3, 4 and 5 are diagrammatic views showing the relative' positions of the coupling mechanism and the outer rotary member at various stages in the revolutionof the latter.

Figs. 6 and 7 l/Vith reference first to Figs. 1 and 2, the

apparatus comprises a hollow cylinder or drum A formmg the inner rotary member are cross sections of the rotary members shovvmg a modified conmounted in a gas tight manner upon' a shaft C which is hollovv7 for a portion of its length, this shaft being carried in bearings C1 and C2 secured to the inner wallsof a fixed outer casing B. The open end of the hollow shaft engages a socket or sleeve C6 secured to the fixedcasmg and constituting the inlet passage for the fluid to be compressed, ports C3 inthe wall of the vhollow shaft establishing communication with the interior of the drum. The solid end of the shaft extends outwardly through an annular chamber 'Bland passes through a stuffing y box on the fixed outer casing. Inclosing the rotary member, this cylinder being mounted on independently adjustable bearings D1 and D2 capable of being locked to the fixed casing in their correct position eccentric to lthose of the drum. The precise form of Vthe drum. The amount of eccentricity and the relative diameters ofthe 4drum and cylinder are then such that there is always contact between the outer periphery of the drum and the inner periphery of the cylinder atone point thrtaghout'each revolu- Pdrum is a cylinder D forming the outer.

tion. The ends of the drum are recessed so ns to form around the hollow shaft an an'- nular chamber E and El between each end ofthedrumaud the adjacent inner end wall of the cylinder, so that only the outer rims4 or edges A? A. of the drum are in sliding contact with the end walls of the cylinder.

Formed in the drum aiid extending from end to end thereof is a radial slot F (Fig. 2) provided with inwardly projecting side walls ll connected by a base F2 and constiv `A and the cylinder D, this vane reciprocating in the slot in the usualmanner as the .drum and cylindrical casing D are rotated,

beingflield in contact with the inner periphery of the cylinder at all times by centrifugal force with or wit-hout the addition of one or more springs.

A suction port H is formed in the drum on one side of the vane through which the fluidto be compressed is di'awn from the Yinterior of the drum into the crescentshaped space between the circumferential periphery of the drum and the inner wall 'of the cylinder D, and on'the opposite side of the vane to the suction poit in the wall of the cylindrical casing D is formed an outlet J for the compressed fluid. The outlet port is conveniently provided with a known form of light spring valve J1 with a suitable guide or cover J2 to retain it upon its seat against the centrifugal force until the pressure of the fluid in the crescentshaped Space causes the valve J1 to open. Both the drum 'A and the cylindrical casing D which rotates with it are inclosed within the outer fluid-tightl casing .B and this is provided with an outlet port B3 through which the compressed fluid is delivered.

To insure a fluid-'tight jointk being maintained along the bearings of the cylinder and between relatively movable parts of the apparatus, lubricant is circula-ted from the base of the fixed. outer casing by a pump P throi'igh the pipe K into the annular chamber B- thence through the passa-ges K1 eand K2 into the interior of the adjustablebearing D1, holes K3 being provided to lubricate this bearing. The lubricant is thus supplied to the chamber E1 formed betweenthe adjacent end of the drum A and cylinder D and thus to the radial slot F in which the vaneG is disposed, the annular chamber E,

the interior of the adjustable bearing D2 and by the conduit K* to the sleeve C6. The lubricant` delivered lnto the chambers E, E1

at the ends of the drum, is thrown outward by centrifugal forceto formlan annular .seal of liquid at each end of the drum and along the inner end of the vane, suitable overflow apertures such as D4 through v70 A the bearing D2 determining the depth of the liquid seal so formed. Any leakage that may take place past the sides of the vane G or past the ends of the drum, will be leak- .age of the lubricant inward into the crescent-shaped s] ace, as this lubricant is unmembers will be entirely prevented and at the same time a bath of lubricant will be provided.

The quantity of liquid delivered into the annular chamber B surrounding the diivingshaft being greater than can escape byy leakage, the surplus will overflow through the passages l)4 provided in the bearing D2 and is thus discharged into a fixedv outer casing B, the lower part of which lforms a reservoir for the lubricant which is thus available for repeated use. A continuous circulation of lubricant is maintained, as for instance by means of the small pump P which draws the lubricant from the reservoir in the base, of the fixed casing and delivers it as above described. The lubricant which 4leaks past the sides ofthe vane G and ends of the drum forms, by centrifugal 4 force, a thin film on the inner circumference of the outer cylinder and thus serves to lubricate the outer end of the vane which bears on the inner periphery of the cylinder, thus insuring the free reciprocation of the vane G within its slot F, and at the saine tiineacting as a seal to prevent the escape of fluid to be compressed past the outerA end of the vane or between those parts of the drum and cylinder which are in contact.

Any lubricant which thus leaks into the crescent-shaped space is finally discharged with the compressed fluid, into the outer casing, suitable baffles such as B4 being provided in the upper part of this casing to prevent its delivery with the compressed fiuid. The

lubricant in the annular reservoir or chamber B1 surrounding the driving shaft C also foi-ins a seal to prevent the escape of coin. pressed fluid or the leakage of air inward when the apparatus is used as a vacuum pump.

' The coupling mechanism whereby the cylindrical casing D is caused to rotate simiiltaneously vwith the drum A and at the sainev angular velocity may vary, but is disposed in the chamber formed between one end of the drumrA and the adjacent-inner end ofl its cylindrical casing DQ Preferablythisr coupling member is at the end of the apparatus remote from the driving shaft C )rojecting members', for example steell keys I .formed on the outer end wall of the drum A and similar members N formed on the inner en d wall D3 of the casing D, respectively engage guides or slots M1. N1 provided in the opposite faces of an annular disk O which is free-to'fioat about the hollow portion of the shaft C. The guides M1 on one face of the disk are at right `angles to those N1 on the other face, so that as the drum A is rotated by means of the driving shaft the projections M thereon move in their'reare shown. The grooves N1 engaged by the.

keysI N secured to the end wall D? of the outerrotary member are formed on the under side of the annular disk O.

When the drum A and the keys M rotate about its center A A through 45 into the position shown in Fig. 4, the keys N are also moved through a similar angle and the disk O, coupling these members A and D slides on the keys M, N into the position -shown in Fig. 4. Further rotation through another '459 brings the disk intothe position shown in Fig. 5.

From the above it will be seen that though not mounted about the same axis, the keys on the two rotary members by engaging their respective grooves in the disk O effect the rotation of the drum and outer rotary member at the same angular velocity.A

The chamber E in which the coupling mechanism is disposed contains suicient lubricant for all the moving parts of this mechanism to be constantly immersed,` a bath of lubricant being thus provided.

In operation, the fluid to bevcompressed is 4drawn vthrough the hollow shaft and open- .,ings C3 into the ,interior of the drum A vand passing through the suction aperture II behind the radial vane G is compressed in the crescent-shaped space as the drum A and casing D rotate. When the pressure Awithin the crescent-shaped space exceeds that with- .in thcfixed casing B, the valve J1 controlling the outlet port J will open, whereupon the fluid thuscompressed is discharged into the fixed casing whence. it is delivered to the lthe discharge port J is provided for the purpose of preventing the Huid within the outer casing rentering the crescentshaped. space. The""heat of compression is taken up by fthe lubricant, which may in turn be cooled by being passed through tubes immersed in cold water' orvin any other known manner after it has been drawn from the fixed casmg by the pump and before it is returned' for repeated use.

.Where such an arrangement is provided the lubricant thus serves the three purposes of lubricating all wearing parts, sealing all parts where leakage ofcompressed fluid might take place,` and carrying away the heat of compression.

The apparatus is especially suited for. compressing gases which lliquefy at low. pressures such as ether, ethyl chlorid, or the like for refrigerating purposes, in which case the heat of compression may be removed in the known manner by allowing the fluid to be compressed to enter the apparatus 1n a saturated or super-saturated condition.

Figs. 6 'and 7 illustrate `a modified construction of apparatus also according to this lnventionhaving two radial slots or compartments and vanes sliding therein instead of one. In this construction a port H1 is formed through the rear side wall of each of the radial slots or compartments F3 instead of being formed through the periphery of the drum A and the Avanes G1'are provided with ports G2 so formed that when' the vanes are. at right angles to a line passingthroughv 100 the centers of the inner and outer rotary members the port in one vane is about to l open while the port in the other vane 4is about to close. This Ais the position shown in Fig. 7. The direction of rot-ation is shown by the arrow and in Fig.' 6 the `.fluid in the space to the left of the lower vane G2 is being compressed while low pressure iuid` is passing from the interior of the druml through the ports H1 and G2 into the crescent-shaped space, the port Gr2` in this position being full open. volume of Huid tionalto twice the area of that part of the crescent-shaped space (which""forms what shown in Fig. 7

E Deliveryports J3 Aare provided through the cylinder Din front of the vanes. G1 in the direction of rotation that is to say on .Y the opposite sides of the vanes to the ports y G1. These delivery ports are provided with suitable valves Jj* similar to the -valves J1 previously described with reference to.

In this construction the keys-.M shown in Fig. 2 are dispensedwith the ends of the vanes G1 engaging with the slots M1 1n the annular disk -O but guides orslots N2 at drawn in during each revolution' is propor- I right angles to those engaged by the ends of the vanes G1 are formed on the opposite face of the disk O and are engaged by projecting keys N3 on the inner end wall of the cylinder D.

As the inner rotary member A is rotated by means of its driving shaft the ends of the vanes (l1 will carry with them the annular disk qO which in turn by engaging the projecting-keys N3 on the end wall of the outer rotary member D effects the rotation of the latter at the sameiangular velocity as the ldrum. Similarly when a single vane is used as in the construction illustrated in Fig. 1 if the radial slot or compartment for the vane is in line with one of the keys M the end of the vane may be'vused to engage the slot in the annular disk O instead of the key, only one key M then being employed on the side opposite to thevane.

Instead of circulating the lubricant byv means of a pump the' circulation may be produced automatically by the difference of pressure which results when the compressor is in operation. This can be done for instance by providing a slnall hole C4 (Fig.

l) through the hollow shaft and omittingl the overflow opening D4 through the bearingmDz. The result of this is that the pressure in the annular chamber E, radial slot or slots, chamber El and'annular chamber B1 will be reduced as communication is established between these spaces and the sucvtion side of the compressor through the small opening C, At the same time the delivery pressure acts on the surface of the lubricant in the base of the fixed casing B- and therefore flows up the pipe K into the annular chamber B1 and thence as previously described into the annular chambers El and E until it reaches the opening C* when a small quantity of the lubricant vwill pass through this opening into the suction side of the Acompressor at each revolution. being finally discharged with the compressed fluid into the fixed outer casing B where it may be se arated from the compressed fluid by the bailes B4 the 'compressed fluid passing out by the opening B3 andthe lubricant fall ing down to the lower part of the casing for further use. A ycontinuous circulation of the lubricant is thus automatically set up so long as the compressor'is in operation without the use of a separate pump. In' such a case the lubricant may be cooled in any known manner. A

It will be appreciated that though de-A scribed as a compressor for fluids theapparatus is equally applicable tol rotary pumps and compressors generally and that the details of construction of the apparatus as a whole or of the coupling mechanism may be modified without departing from this invention. In the following claims the l. In a rotary pump the combination of an outer rotary member, an inner rotary member mounted eccentrically therein "and adapted to rotate therewith at the same angular velocity, a radial vane extending across the space between the inner and outer rotary members, a fixed outer casing inclosing both rotary members, and means for maintaining a seal of liquid in the joints between the relatively moving parts .of the apparatus which inclose the chamber in which the air is compressed' whereby these parts are lubricatedl and escape of compressed fluid is prevented. 2. In a rotary pump the combination of an outer rotary member having a discharge port `therein, an inner rotary member eccentri a vane mounted to slide in the radial comchamber at each end of the inner rotary member, a radial compartment formed in the circumferential wall of the inner rotary member said compartment connecting the chambers, a vane mounted to slide in the radial compartment, means` for supplying lubricant under pressure to the chambers and lto the compartment for the` purposel de-` inclsing both vrotary members and means or adjusting the scribed, a fixed outer casin position of tlre outer rotary member relatively to the inner rotary member.

4. In a rotary pump the combination of-an outer rotary member, an inner rotary member mounted eccentrically therein, "mechanism couplingthe inner 'and outer rotary members so that. they' rotate at the same angular velocity such lcoupling mechanism comprising an annular .disk having guides on its opposite faces, the guides on one.

face being at right anglesv to those on the other, sald disk being mounted between adj acent ends of the lnner and outer rotary mem# bers, pr'ojections on said adjacent ends so engaging'the guides as to reciprocate the disk relatively to the axes of the rotary members, a radial vane extending across the space between the inner andouter rotary members and a fixed outer casing inclosing both rotary members.

5. In a rotary 'pump the combination of an outer rotary member, an inner rotarymember mounted eccentrically therein, mechanism coupling the inner and outer rotaryl members so that they rotate at the same angular velocity such coupling mechanism comprising an annular disk having guides on its opposite faces, the guides on one face. being at right angles to those on the other, said disk being mounted between adjacent ends of the inner and outer rotary members, projections on saidI adjacent endsv so engaging the guides as to reciprocate the disk rela- 'tively to the axes of the rotary members, -a

radial vanerextending across the space bel tween the inner and outer rotary members, a

l fixed outer casing inclosing both rotary members," a'rid means for maintaining a liquid seal between relatively moving parts of the apparatus for the purpose described.

6. In a rptary pump the combination of an outer rotary member, an inner rotary member mounted eccentrically therein, mechanism coupling the inner and outer rotaryl members so that they rotate at the same angular velocity such coupling mechanism comprising an annular disk `having guides on its opposite faces, the guides on one face being at ri ht angles to those on the other, said disk eing mounted between adjacent ends of the inner and outer rotary members, projections on said adjacent ends so vengaging the guides as to reciprocate' the disk relaltively to the axes of the rotary members, a

radial vane extending acrossy the 'space bev tween the inner and outer rotary members,

having two diametrically' opposed radial compartments, vanes -slidably mounted in suctionsaid compartments controlling ports formed'in the compartments and so disposed that when the vanesjare at right angles to a line passing through the centers of the inner and outer 'rotary members one suction port is about to o en and the other about to close, outlet va ves in the outer rotary member on the opposite sides of the vanes to the suctionpports, a chamber at each end of the inner rotary member such chambers communicating with each other bymeans of the radial compartments and a fixed outer casing inclosing the rotarymembers. r I i '8.- In a rotary pumpthe combination of an outer rotary member, an inner rotary member mounted eccentrically therein and adapted to rotate 'therewith at the same angular veloci y', said inner rotary member having two iametrically opposed -radial compartments,vanes s'lidably. mounted in said compartments controlling suction ports formed in the compartments and so disangles t0 aline passing through the centers of the inner and outer rotary members one suction port is about to open and the other about to close, outlet valves in the outer rotary member on theopposite sides of the posed that when the vanes are at right' vanes to the suction ports, a chamber at each end of the inner rotary member such chambersjcommunicating with each other by means of the radial compartments,l a ixed 'outer casing inclosing the rotary members,

and means for supplying' lubricant under pressure to the chambers and compartments for the purpose described.

9. In a rotary pum the combination of an `=outer rotary mem er, an inner rotary member mounted eccentrically therein and j adapted to rotate therewith at the same angular velocity said inner rotary member lhaving' two diametrically opposed radial compartments, slidable vanes mounted in said compartments controlling suction ports formed therein, outlet valves inthe outerl rotary member on the opposite sidesof the @vanes to the`suction ports, a hollow shaft communicating with the 'interior of the inner rotary member and a fixed outer casing inclosing the rotary memberscthe whole arrangement being such that the volume of Huid drawn in during each revolution is proportional to twice the area of the trun cated crescent-shaped space between the two vanes when they are atright angles to a line passing through the centers of the inner and outer rotary members.

- 1,0. In a rotary pump the combination of an outer rotary member, an inner rotary member mounted eccentrically therein, an annular disk between adjacent ends of the rotary members, lmeans for driving one of iio said rotary members, .and slidable engaging means betweengthe disk and the adjacent `ends of the rotary members whereby said members 'are caused to rotate at the same angular velocity substantially as set forth.

A 11. In a rotary pump the combination'of an outer rotary member an inner rotary member mounted eccentrically therein and having diametrically. opposed radial coin- .partments, vanes mounted in said compartis'o ments, an annular disk between adjacent ends of the rotary members, guides 1n sald dlsk engaglng the ends of the venes, other guides in said disk at right angles to the vane-engaging Guides, and projections on the adjacent Wal of the outer rotal'ymember making sliding engagement with said other guides for the purpose described and means for driving one of the rotary mem bers. 10

In testimony whereof I have signed my name to this speciication.

RICHARD JOHN CRACKNELL'. 

